Complete the recursive formula of the arithmetic sequence $-15, -11, -7, -3,...$. $c(1)=$
The first term is $-15$ and the common difference is $4$. ${+4\,\curvearrowright}$ ${+4\,\curvearrowright}$ ${+4\,\curvearrowright}$ $-15,$ $-11,$ $-7,$ $-3,...$ This is the recursive formula of $-15, -11, -7, -3,...$ $\begin{cases} c(1)=-15 \\\\ c(n)=c(n-1)+4 \end{cases}$